Recently, in a medical diagnosis field, it is becoming easier for doctors to share a large amount of data with an advancement of digitalization of medical images and image interpretation reports. Here, an image interpretation report is a text data item indicating a diagnosis made by an image interpreter such as a doctor based on a medical image. In addition, image interpretation reports stored in Picture Archiving and Communication Systems (PACS) which are systems for storing and communicating images are managed in an associated manner, and the stored past image interpretation reports are desired to be used secondarily in an effective manner. A method for using such image interpretation reports secondarily is to automatically present reference cases for medical images which are interpretation targets based on which a diagnosis is made. In relation to this, an effort for supporting a decision making related to a diagnosis is expected.
As a conventional technique for realizing presentation of such reference cases, Patent Literature 1 proposes a method of searching out and presenting similar cases using image feature quantities of medical images corresponding to image interpretation reports stored in a database and text information included in the image interpolation reports. More specifically, in the search of the similar cases, a first search is performed to search out image interpretation reports which show similar image forms from among the image interpretation reports. Subsequently, a second search is performed to extract representative keywords between text information items in the image interpretation reports searched out in the first search, select image feature quantities associated in advance with the extracted keywords, and calculate degrees of similarity between the cases based on the selected image feature quantities. The text information items described in the image interpretation report show a viewpoint of the image interpreter. In other words, the method disclosed in Patent Literature 1 makes it possible to present the similar cases searched out based on the viewpoint of the image interpreter, on condition that images and keywords are associated with each other in advance.